Apparatus for separating and removing a dangerous substance from an exhaust gas

Abstract

In order to separate and remove a dangerous substance such as yellow phosphorus from exhaust gas generated in a semiconductor fabricating process by chemical vapor deposition, the exhaust gas is bathed in operating oil of a cooled oil tank of an oil-sealed rotary vacuum pump so that molecules of the yellow phosphorus or the like are caught by the cooled operating oil so as to be enveloped in the operating oil. Thus, a mixture operating oil of the substance and the operating oil is generated in the form of colloid. The mixture operating oil is passed through an oil filter of a filtration device so that the substance such as yellow phosphorus is precipitated by the filter and then the substance is removed. Meanwhile, the operating oil as a filtrate from which the substance has been filtered is cooled by an oil-temperature controller, and then returned to the oil-sealed rotary vacuum pump. Thus, the exhaust gas suctioned into the oil tank of the vacuum pump is ordinarily made contact with the cooled operating oil thereby enhancing the efficiency of separating the substance such as yellow phosphorus.

I claim: 
     
       1. A separation and removal apparatus for separating and removing a substance from exhaust gas, said separation and removal apparatus comprising: an oil-sealed rotary vacuum pump for suctioning the exhaust gas to separate the substance from the exhaust gas and mix the substance with operating oil in the oil-sealed rotary vacuum pump thereby generating a mixture operating oil of the substance and the operating oil, and discharging the rest of the exhaust gas from which the substance has been separated;   a filtration device connected to the oil-sealed rotary vacuum pump and having a filter for filtering and precipitating the substance from the mixture operating oil generated in the oil-sealed rotary vacuum pump;   an oil-temperature control means connected to the filtration device and the oil-sealed rotary vacuum pump and having a temperature control element for changing to a set temperature the temperature of filtered operating oil from which the substance has been removed by the filtration device to maintain the viscosity of the operating oil to above a preselected level;   a circulating pump for circulating the operating oil so that the operating oil in the oil-sealed rotary vacuum pump returns to the oil-sealed rotary vacuum pump through the filtration device and the oil-temperature control means;   an operating-oil temperature sensor for sensing a temperature of the operating oil in the oil-sealed rotary vacuum pump; and   a controller for controlling the temperature control element of the oil-temperature control means based on an output signal of the operating-oil temperature sensor so that the temperature of the operating oil which has been sensed by the operating-oil temperature sensor reaches to the set temperature.   
     
     
       2. The separation and removal apparatus according to claim 1, wherein the controller controls the flow-rate control mechanism and the temperature control element of the oil-temperature control means so that the temperature of the operating oil sensed by the oil-temperature sensor reaches to the set temperature. 
     
     
       3. The separation and removal apparatus according to claim 1, wherein the filter of the filtration device is exchangeable. 
     
     
       4. The separation and removal apparatus according to claim 1, wherein the exhaust gas is generated in a semiconductor fabricating process by chemical vapor deposition and the substance is white phosphorus included in the exhaust gas. 
     
     
       5. The separation and removal apparatus according to claim 4, wherein the operating oil is fluorinated oil. 
     
     
       6. The separation and removal apparatus according to claim 4, wherein the oil-sealed rotary vacuum pump conducts the exhaust gas to an oil tank for the operating oil and bathes the exhaust gas in the oil tank to separate the substance from the exhaust gas and mix the substance with the operating oil, thereby generating the mixture operating oil of the substance and the operating oil. 
     
     
       7. The separation and removal apparatus according to claim 6, wherein the temperature of the operating oil during bathing the exhaust gas in the operating oil of the oil tank is 10° to 15° C.